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<li class="navelem"><a class="el" href="../../d2/d75/namespacecv.html">cv</a></li><li class="navelem"><a class="el" href="../../dc/d07/classcv_1_1GComputationT.html">GComputationT</a></li>  </ul>
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<div class="title">cv::GComputationT&lt; typename &gt; Class Template Reference</div>  </div>
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<p>This class is a typed wrapper over a regular <a class="el" href="../../d9/dfe/classcv_1_1GComputation.html" title="GComputation class represents a captured computation graph. GComputation objects form boundaries for ...">GComputation</a>.  
 <a href="../../dc/d07/classcv_1_1GComputationT.html#details">More...</a></p>

<p><code>#include &lt;opencv2/gapi/gtyped.hpp&gt;</code></p>
<a name="details" id="details"></a><h2 class="groupheader">Detailed Description</h2>
<div class="textblock"><h3>template&lt;typename&gt;<br />
class cv::GComputationT&lt; typename &gt;</h3>

<p>This class is a typed wrapper over a regular <a class="el" href="../../d9/dfe/classcv_1_1GComputation.html" title="GComputation class represents a captured computation graph. GComputation objects form boundaries for ...">GComputation</a>. </p>
<p><code>std::function&lt;&gt;</code>-like template parameter specifies the graph signature so methods so the object's constructor, methods like <code>apply()</code> and the derived <code>GCompiledT::operator()</code> also become typed.</p>
<p>There is no need to use <a class="el" href="../../d2/d75/namespacecv.html#a4941eb8cbe70b8c7187bc8459af7653b">cv::gin()</a> or <a class="el" href="../../d2/d75/namespacecv.html#ac82b8a261b82157293b603b55c096a9e">cv::gout()</a> modifiers with objects of this class. Instead, all input arguments are followed by all output arguments in the order from the template argument signature.</p>
<p>Refer to the following example. Regular (untyped) code is written this way:</p>
<div class="fragment"><div class="line">    <span class="comment">// Untyped G-API ///////////////////////////////////////////////////////////</span></div><div class="line">    <a class="code" href="../../d9/dfe/classcv_1_1GComputation.html">cv::GComputation</a> cvtU([]()</div><div class="line">    {</div><div class="line">        <a class="code" href="../../df/daa/classcv_1_1GMat.html">cv::GMat</a> in1, in2;</div><div class="line">        <a class="code" href="../../df/daa/classcv_1_1GMat.html">cv::GMat</a> out = <a class="code" href="../../da/dd3/group__gapi__math.html#ga3fec036f5cf3f6cb8c2633c109085f0b">cv::gapi::add</a>(in1, in2);</div><div class="line">        <span class="keywordflow">return</span> <a class="code" href="../../d9/dfe/classcv_1_1GComputation.html">cv::GComputation</a>({in1, in2}, {out});</div><div class="line">    });</div><div class="line">    std::vector&lt;cv::Mat&gt; u_ins  = {in_mat1, in_mat2};</div><div class="line">    std::vector&lt;cv::Mat&gt; u_outs = {out_mat_untyped};</div><div class="line">    cvtU.<a class="code" href="../../d9/dfe/classcv_1_1GComputation.html#aa25bc73f7cba9bb2f9992edaa248f868">apply</a>(u_ins, u_outs);</div></div><!-- fragment --><p> Here:</p>
<ul>
<li><a class="el" href="../../d9/dfe/classcv_1_1GComputation.html" title="GComputation class represents a captured computation graph. GComputation objects form boundaries for ...">cv::GComputation</a> object is created with a lambda constructor where it is defined as a two-input, one-output graph.</li>
<li>Its method <code>apply()</code> in fact takes arbitrary number of arguments (as vectors) so user can pass wrong number of inputs/outputs here. C++ compiler wouldn't notice that since the <a class="el" href="../../d9/dfe/classcv_1_1GComputation.html" title="GComputation class represents a captured computation graph. GComputation objects form boundaries for ...">cv::GComputation</a> API is polymorphic, and only a run-time error will be generated.</li>
</ul>
<p>Now the same code written with typed API:</p>
<div class="fragment"><div class="line">    <span class="comment">// Typed G-API /////////////////////////////////////////////////////////////</span></div><div class="line">    <a class="code" href="../../dc/d07/classcv_1_1GComputationT.html">cv::GComputationT&lt;cv::GMat (cv::GMat, cv::GMat)&gt;</a> cvtT([](<a class="code" href="../../df/daa/classcv_1_1GMat.html">cv::GMat</a> m1, <a class="code" href="../../df/daa/classcv_1_1GMat.html">cv::GMat</a> m2)</div><div class="line">    {</div><div class="line">        <span class="keywordflow">return</span> m1+m2;</div><div class="line">    });</div><div class="line">    cvtT.apply(in_mat1, in_mat2, out_mat_typed1);</div><div class="line"></div><div class="line">    <span class="keyword">auto</span> cvtTC =  cvtT.compile(<a class="code" href="../../d3/d0c/group__gapi__meta__args.html#ga0d1b4f7d1dbc43b5ac9ddd6454348f0c">cv::descr_of</a>(in_mat1), <a class="code" href="../../d3/d0c/group__gapi__meta__args.html#ga0d1b4f7d1dbc43b5ac9ddd6454348f0c">cv::descr_of</a>(in_mat2));</div><div class="line">    cvtTC(in_mat1, in_mat2, out_mat_typed2);</div></div><!-- fragment --><p> The key difference is:</p>
<ul>
<li>Now the constructor lambda <em>must take</em> parameters and <em>must return</em> values as defined in the <code><a class="el" href="../../dc/d07/classcv_1_1GComputationT.html" title="This class is a typed wrapper over a regular GComputation. ">GComputationT</a>&lt;&gt;</code> signature.</li>
<li>Its method <code>apply()</code> does not require any extra specifiers to separate input arguments from the output ones</li>
<li>A <code>GCompiledT</code> (compilation product) takes input/output arguments with no extra specifiers as well. </li>
</ul>
</div><hr/>The documentation for this class was generated from the following file:<ul>
<li>opencv2/gapi/<a class="el" href="../../dd/d07/gtyped_8hpp.html">gtyped.hpp</a></li>
</ul>
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